In a massacre of unprecedented savagery that brings Syria close to civil war, some 32 children and 60 adults have been slaughtered in villages in the Houla area of central Syria.

Anti-government militants blame pro-regime gunmen for carrying out the butchery in which children and their parents were hacked and shot to death.

The figure for the number of children and adults killed was confirmed in an interview with The Independent on Sunday by General Robert Mood, the head of the team of 300 UN observers which is seeking to reduce the level of violence. "My patrols went into the village," he said. "I can verify that they counted 32 children under 10 killed. In addition, there were more than 60 adults dead."

General Mood would not explain how the villagers died, but horrific pictures posted on YouTube appear to show that they were shot or knifed to death, some having their throats cut. The small bodies of the children were covered in sheets as they were taken by survivors screaming in grief and disbelief from the houses where they had been murdered.

The massacre is the worst single incident in Syria's 14-month crisis because it involved the deliberate murder of children as well as adults. Militants say the perpetrators were pro-regime gunmen, known as the shabiya, who had captured Houla. If true, the shabiya may have been members of the Alawite sect, which is supportive of the government. Alawites inhabit a string of villages south of Houla, which is 25km north-west of Homs. The Syrian leadership is largely drawn from the Alawite sect.

General Mood said that fighting around Houla started on Friday evening with the use of "tanks, artillery, rocket-propelled grenades, and heavy machine guns". This implied an attack by government forces since the insurgent Free Syrian Army does not have heavy weapons. This confirms the militants' story that there had been big anti-government protests on Friday in Houla, where there have previously been many anti-government demonstrations.

The calculated slaughter of Sunni villagers and their children by Alawites brings a new level of violence to Syria and propels it towards sectarian civil war. On Saturday, Damascus was quiet aside from one protest in an outlying district, but fighting has intensified at Rastan, north of Homs. Observers from the UN Supervision Mission in Syria (UNSMS) have mediated a ceasefire there, leaving insurgents in control of the town. But this straddles the main highway linking Damascus and Aleppo, so the government is unlikely to allow the Free Syrian Army to hold the town for long.

The Houla massacre could mark a crucial stage in the war in Syria because it will energise the insurgents inside and outside the country. It will make it more difficult for any compromise or new ceasefire to be arranged between President Bashar Assad and his opponents. It will increase hatred between Sunni and Alawites, a heterodox branch of Shia Islam. This has already been seen in the past week, with 11 Shia pilgrims kidnapped by insurgents in Syria and 10 people killed in associated violence in Lebanon. Houla is not far from the Lebanese border, and the latest atrocity is similar to what happened in the Lebanese civil war between 1975 and 1990, when different communities repeatedly massacred each other.

The pictures of the dead children of Houla are likely to create an international outcry and underline that the ceasefire arranged by the UN-Arab League envoy Kofi Annan is foundering. General Mood confirmed yesterday that there was no real ceasefire in Syria and said that there could not be an effective one until the combatants themselves implemented it. He emphasised that unarmed UN monitors cannot impose a truce, though in some areas, such as Homs, they have succeeded in "calming" the situation. He said: "The solution to the Syria crisis lies in the hands of the Syrian government, the fragmented opposition, and those outside fuelling the crisis by supplying arms and explosives."

Mr Annan is due in Damascus in the next few days to try to patch up a new ceasefire, but neither the government nor its opponents have carried through on past agreements. The government suppression of peaceful protest with gunfire and mass detentions has continued. At the same time, the Islamicisation and militarisation of the opposition is frightening minorities, such as the Alawites, Christians and Druze. The government is targeting moderate and secular opposition in order to present a stark choice to Syrians, and the world, between itself and Islamic fundamentalists.

On Saturday, the Foreign Secretary, William Hague, said: "There are credible and horrific reports that a large number of civilians have been massacred, including children. Our urgent priority is to ensure those responsible are held to account. We will be calling for an urgent session of the UN Security Council in the coming days. The Assad regime must cease all military operations."

The President and his First Lady... and their people

He is the President; she is the First Lady; they are dead children. He governs but doesn't protect; she shops and doesn't care; they will never grow old. His father was an autocrat; hers a Harley Street doctor; theirs are bereaved. He will sleep in his bed tonight; so will she; they will be in their graves. However you conjugate the lives of the Syrian leader and his people, there is something very wrong.

Two days ago, they were all alive. He and she in their gilded residence, looking much as they do in this photograph - he sharp-suited, she sun-glassed and with a watch of gold on her wrist. The children were in their ramshackled homes in Houla, poor but alive. Then the men of war came. When they left, the children were as you see them here in this, the most grotesque picture yet to emerge from this land of the alleged ceasefire.

There are still photographs of this scene, and video. And over the footage that would bear more than enough testimony to the redundant regime of Assad, the voice of a man can be heard screaming. "These are all children!" he cries, shrill with angry despair, "Watch, you dogs, you Arabs, you animals – look at these children, watch, just watch!"

And one hopes that those on the United Nations Security Council, when it reconvenes, will look into the staring eyes of these dead children and remember the hollow words of Assad's wife when she simpered that she "comforts the families" of her country's victims.